Effect of revascularization on left ventricular remodeling in patients with heart failure from severe chronic ischemic left ventricular dysfunction

Current status and perspectives of nuclear cardiology

Nuclear cardiology has long been used to identify myocardial ischemia for appropriate treatment strategies for stable coronary artery disease (CAD). After the Ischemia Trial, it is time to reevaluate the significance of ischemia assessment. Functional imaging continues to play pivotal role in detecting microcirculatory disturbances. PET provides a clear image of blood flow distribution and is useful for the quantitative evaluation of myocardial flow reserve (MFR), which plays an important role in predicting treatment strategies and improving prognosis in CAD. Heart failure has become a major area of focus in cardiovascular medicine. Radionuclide imaging has been widely applied in this field. FDG PET is useful in identifying cardiac sarcoidosis and active inflammation. Clinical values of I-123 MIBG and BMIPP SPECT have been reported worldwide from Japan. Additionally, clinical experiences of Tc-99m pyrophosphate imaging have recently gained attention for assessing cardiac amyloidosis. Cardiac PET/CT and PET/MR imaging permit combined assessment of metabolic/functional/structural analyses of various cardiac diseases. While other non-invasive imaging modalities have rapidly been developed, the roles of radionuclide imaging remain to be valuable for early and accurate diagnosis and patient management in most cases of chronic CAD and various cardiovascular diseases.

Comparison of Contrast Enhanced Low-Dose Dobutamine Stress Echocardiography with 99mTc-Sestamibi Single-Photon Emission Computed Tomography in Assessment of Myocardial Viability

INTRODUCTION

Dobutamine stress echocardiography (DSE) and myocardial perfusion scan are the commonly used modalities to detect viable myocardium. DSE is comparatively cheaper and widely available but has a lower sensitivity.

AIM

We aimed to compare contrast-enhanced low-dose dobutamine echocardiography (LDDE) and gated 99mTc-sestamibi myocardial perfusion scan (MPS) for the degree of agreement in the detection of myocardial viability.

METHODS

We studied 850 left ventricular segments from 50 patients (42 men, mean age 55.5 years), with coronary artery disease and left ventricular systolic dysfunction (ejection fraction < 40%), using contrast-enhanced LDDE and 99mTc-Sestamibi gated SPECT. Segments were assessed for the presence of viability by both techniques and head to head comparisons were made.

RESULTS

Adequate visualisation increased from 80% in unenhanced segments to 96% in contrast-enhanced segments. Of the total 850 segments studied, 290 segments (34.1%) had abnormal contraction (dysfunctional). Among these, 138 were hypokinetic (16.2% of total), 144 were severely hypokinetic or akinetic (16.9% of total), and 8 segments were dyskinetic or aneurismal (0.9% of total). Among 151 segments considered viable by technetium, 137 (90.7%) showed contractile improvement with dobutamine; in contrast, only 8 of the 139 segments (5.7%) considered nonviable by technetium had a positive dobutamine response. The per cent of agreement between technetium uptake and a positive response to dobutamine was 78.6% with kappa = 0.63, suggestive of a substantial degree of agreement between the two modalities.

CONCLUSION

Use of contrast-enhanced LDDE significantly increased the adequate endocardial border visualisation. Furthermore, this study showed a strong degree of agreement between the modalities in the detection of viable segments. So, contrast-enhanced LDDE appears to be a safe and comparable alternative to MPS in myocardial viability assessment.

Magnetic Resonance Imaging of Reverse Remodeling After Coronary Revascularization in Ischemic Heart Disease - Morphologic Evaluation

BACKGROUND

Coronary revascularization has been shown to induce left ventricular (LV) reverse remodeling (RR). The serial morphologic changes in enhanced necrotic tissue during RR on cardiac magnetic resonance imaging (CMR) have not been investigated.Methods and Results:This retrospective study included 26 patients with severe LV systolic dysfunction (ejection fraction [EF], <35% on echocardiography) who underwent CMR before and >6 months after surgical revascularization. Of 26 patients, 20 had a reduction of ≥10% in end-diastolic and end-systolic volumes (classified as RR group). The RR group had improvement in EF after revascularization (28.8±6.6% vs. 40.6±7.8%, P<0.0001), and no change in absolute infarct mass (17.3±10.9 g vs. 17.5±10.4 g, P=0.8), but an increase in relative infarct mass (21.0±13.7% vs. 26.5±19.4%, P=0.01) due to reduction of myocardial mass after revascularization. Significant increase in regional transmural extent (30.3±21.6 vs. 42.6±22.8, P<0.0001) and in thickness of enhanced tissue (4.2±1.5 mm vs. 5.9±1.8 mm, P<0.0001) was found in the RR group. No significant differences were observed in any of the variables in the non-RR group.

CONCLUSIONS

In patients with chronic myocardial ischemic dysfunction, significant volume reduction after revascularization led to significant increase in regional transmural extent of the enhanced area without a change in absolute infarct mass, on CMR. (Circ J 2016; 80: 2513-2519).

Non-invasive imaging in detecting myocardial viability: Myocardial function versus perfusion

Coronary artery disease (CAD) is the most prevalent and single most common cause of morbidity and mortality [1] with the resulting left ventricular (LV) dysfunction an important complication. The distinction between viable and non-viable myocardium in patients with LV dysfunction is a clinically important issue among possible candidates for myocardial revascularization. Several available non-invasive techniques are used to detect and assess ischemia and myocardial viability. These techniques include echocardiography, radionuclide images, cardiac magnetic resonance imaging and recently myocardial computed tomography perfusion imaging. This review aims to distinguish between the available non-invasive imaging techniques in detecting signs of functional and perfusion viability and identify those which have the most clinical relevance in detecting myocardial viability in patients with CAD and chronic ischemic LV dysfunction. The most current available studies showed that both myocardial perfusion and function based on non-invasive imaging have high sensitivity with however wide range of specificity for detecting myocardial viability. Both perfusion and function imaging modalities provide complementary information about myocardial viability and no optimum single imaging technique exists that can provide very accurate diagnostic and prognostic viability assessment. The weight of the body of evidence suggested that non-invasive imaging can help in guiding therapeutic decision making in patients with LV dysfunction.

New vessel formation in the context of cardiomyocyte regeneration--the role and importance of an adequate perfusing vasculature

The history of revascularization for cardiac ischemia dates back to the early 1960's when the first coronary artery bypass graft procedures were performed in humans. With this 50 year history of providing a new vasculature to ischemic and hibernating myocardium, a profound depth of experience has been amassed in clinical cardiovascular medicine as to what does, and does not work in the context of cardiac revascularization, alleviating ischemia and adequacy of myocardial perfusion. These issues are of central relevance to contemporary cell-based cardiac regenerative approaches. While the cardiovascular cell therapy field is surging forward on many exciting fronts, several well accepted clinical axioms related to the cardiac arterial supply appear to be almost overlooked by some of our current basic conceptual and experimental cell therapy paradigms. We present here information drawn from five decades of the clinical revascularization experience, review relevant new data on vascular formation via cell therapy, and put forward the case that for optimal cell-based cardiac regeneration due attention must be paid to providing an adequate vascular supply.

Late onset oral treatment with tranilast following large myocardial infarction has no beneficial effects on cardiac remodeling and mortality in rats

Tranilast (Tra) reduces intracardiac interstitial fibrosis in the animal models of hypertensive heart failure and diabetic cardiomyopathy by inhibiting cardiac fibroblasts. The present study examined whether Tra has long-term effects on the cardiac remodeling in the remote area of the left ventricle (LV) following myocardial infarction (MI) in the rat. Treatment with Tra (n=40; 150 mg/kg twice daily) or placebo (Plac, n=36) was started at day 28 after induction of a large MI or sham-operation (ShO, n=18) in female Lewis rats. Collagen content was determined using high-performance liquid chromatography. Large MI led to a significant hypertrophy of the two ventricles, a severe dilatation of the LV and a shift of the chamber stiffness variables in the pressure volume curves. The six-month survival rates were Tra, 62.5%; Plac, 75%; and ShO, 100%. No significant difference was identified between Tra and Plac regarding survival rate and collagen content. Treatment with the anti-inflammatory and antifibrotic drug, Tra, started four weeks after the induction of a large MI in the rat, did not attenuate or positively influence remodeling in chronic ischemic heart failure and survival. Further studies are required to explore the effects of Tra on cardiac myocytes post-MI in more detail.

Prediction of long-term segmental and global functional recovery of hibernating myocardium after revascularisation based on low dose dobutamine and late gadolinium enhancement cardiovascular magnetic resonance

BACKGROUND

This study sought to evaluate the relation between long-term segmental and global functional outcome after revascularisation in patients with chronic ischaemic left ventricular dysfunction (LVD) and baseline markers of viability: late gadolinium enhancement (LGE) transmurality and contractile reserve (CR).

METHODS

Forty-two patients with chronic ischaemic LVD underwent low-dose dobutamine- (LDD) and late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) before surgical or percutaneous revascularisation. Regional and global left ventricular (LV) functions and LGE were repeatedly assessed 6 ± 1 and 35 ± 6 months after revascularisation. In total, 319 at baseline dysfunctional and successfully revascularised segments were available for statistical analysis.

RESULTS

The likelihood of long-term functional improvement was directly related to the presence of CR and inversely related to both the LGE and the degree of contractile dysfunction at baseline. The time course of functional improvement was protracted, with significantly more delay in segments with more extensive LGE (p = 0.005) and more severe contractile dysfunction at baseline (p = 0.002). The presence of CR was the predictor of earlier functional improvement (p < 0.0001). Using a definition of viable segment as a segment without any LGE or with any LGE and producing CR during LDD stimulation, ≥ 55% of viable segments from all dysfunctional and revascularised segments in a patient was the only independent predictor of significant improvement (≥ 5%) in the left ventricular ejection fraction (LVEF) after revascularisation, with a 72% sensitivity and an 80% specificity (AUC 0.76, p = 0.014). Reverse LV remodelling was observed in patients who had a significant amount of viable myocardium successfully revascularised.

CONCLUSIONS

In patients with chronic ischaemic LVD, improvement of dysfunctional but viable myocardium can be considerably delayed. Both the likelihood and the time course of functional improvement are related to the LGE, CR and the degree of contractile dysfunction at baseline. At 35 ± 6 months after revascularisation, patients with ≥55% of viable segments from all dysfunctional and revascularised segments significantly improve LVEF and experience reverse LV remodelling. A combination of LDD-CMR and LGE-CMR is a simple and powerful tool for identifying which patients with impaired LV function will benefit from revascularisation.

Myocardial scar identified by magnetic resonance imaging can predict left ventricular functional improvement after coronary artery bypass grafting

BACKGROUND

Previous studies have shown that viable myocardium predicts recovery of left ventricular (LV) dysfunction after revascularization. Our aim was to evaluate the prognostic value of myocardial scar assessed by late gadolinium-enhanced cardiovascular magnetic resonance imaging (LGE-CMR) on functional recovery in patients undergoing coronary artery bypass grafting (CABG).

METHODS

From November 2009 to September 2012, 63 patients with reduced left ventricular ejection fraction (LVEF) referred for first-time isolated CABG were prospectively enrolled, 52 were included in final analysis. LV functional parameters and scar tissue were assessed by LGE-CMR at baseline and 6 months after surgery. Patency of grafts was evaluated by computed tomography angiography (CTA) 6 months post-CABG. Predictors for global functional recovery were analyzed.

RESULTS

The baseline LVEF was 32.7 ± 9.2%, which improved to 41.6 ± 11.0% 6 months later and 32/52 patients improved LVEF by ≥ 5%. Multivariate logistic regression analysis showed that the most significant negative predictor for global functional recovery was the number of scar segments (Odds ratio 2.864, 95% Confidence Interval 1.172-6.996, p = 0.021). Receiver-Operator-Characteristic (ROC) analysis demonstrated that ≤ 4 scar segments predicted global functional recovery with a sensitivity and specificity of 85.0% and 87.5%, respectively (AUC = 0.91, p<0.001). Comparison of ROC curves also indicated that scar tissue was superior to viable myocardium in predicting cardiac functional recovery (p<0.001).

CONCLUSIONS

Our findings indicated that scar tissue on LGE-CMR is an independent negative predictor of cardiac functional recovery in patients with impaired LV function undergoing CABG. These observations may be helpful for clinicians and cardiovascular surgeons to determine which patients are most likely to benefit from surgical revascularization.

Radionuclide imaging in stage B heart failure

This article discusses currently available radionuclide techniques in the diagnostic and prognostic evaluation of patients with chronic heart failure, with a focus on stage B/asymptomatic left ventricular dysfunction. Radionuclide imaging is promising for such patients because it can simultaneously determine left ventricular function, evaluate for the presence of obstructive coronary disease, determine the extent of viable myocardium, and evaluate dyssynchronous left ventricular contraction. Radionuclide imaging can thus provide important noninvasive insights into the pathophysiology, prognosis, and management of patients with asymptomatic left ventricular dysfunction as well as more advanced heat failure.

The Occluded Artery Trial (OAT) Viability Ancillary Study (OAT-NUC): influence of infarct zone viability on left ventricular remodeling after percutaneous coronary intervention versus optimal medical therapy alone

BACKGROUND

The Occluded Artery Trial (OAT) showed no difference in outcomes between percutaneous coronary intervention (PCI) versus optimal medical therapy (MED) in patients with persistent total occlusion of the infarct-related artery 3 to 28 days post-myocardial infarction. Whether PCI may benefit a subset of patients with preservation of infarct zone (IZ) viability is unknown.

METHODS AND RESULTS

The OAT nuclear ancillary study hypothesized that (1) IZ viability influences left ventricular (LV) remodeling and that (2) PCI as compared with MED attenuates adverse remodeling in post-myocardial infarction patients with preserved viability. Enrolled were 124 OAT patients who underwent resting nitroglycerin-enhanced technetium-99m sestamibi single-photon emission computed tomography (SPECT) before OAT randomization, with repeat imaging at 1 year. All images were quantitatively analyzed for infarct size, IZ viability, LV volumes, and function in a core laboratory. At baseline, mean infarct size was 26% ± 18 of the LV, mean IZ viability was 43% ± 8 of peak uptake, and most patients (70%) had at least moderately retained IZ viability. There were no significant differences in 1-year end-diastolic or end-systolic volume change between those with severely reduced versus moderately retained IZ viability, or when compared by treatment assignment PCI versus MED. In multivariable models, increasing baseline viability independently predicted improvement in ejection fraction (P = .005). There was no interaction between IZ viability and treatment assignment for any measure of LV remodeling.

CONCLUSIONS

In the contemporary era of MED, PCI of the infarct-related artery compared with MED alone does not impact LV remodeling irrespective of IZ viability.

Prediction of global left ventricular functional recovery in patients with heart failure undergoing surgical revascularisation, based on late gadolinium enhancement cardiovascular magnetic resonance

BACKGROUND

The new gold standard for myocardial viability assessment is late gadolinium enhancement-cardiovascular magnetic resonance (LGE-CMR); this technique has demonstrated that the transmural extent of scar predicts segmental functional recovery. We now asked how the number of viable and number of viable+normal, segments predicted recovery of global left ventricular (LV) function in patients undergoing CABG. Finally, we examined which segmental transmural threshold of scarring best predicted global LV recovery.

METHODS AND RESULTS

Fifty patients with reduced LV ejection fraction (EF) referred for CABG were recruited, and 33 included in this analysis. Patients underwent CMR to assess LV function and viability pre-operatively at 6 days and 6 months. Mean LVEF 38% ± 11, which improved to 43% ± 12 after surgery. 21/33 patients improved EF by ≥3% (EF before 38% ± 13, after 47% ± 13), 12/33 did not (EF before 39% ± 6, after 37% ± 8). The only independent predictor for global functional recovery after revascularisation was the number of viable+normal segments: Based on a segmental transmural viability cutoff of <50%, ROC analysis demonstrated ≥10 viable+normal segments predicted ≥3% improvement in LVEF with a sensitivity of 95% and specificity of 75% (AUC = 0.9, p < 0.001). Transmural viability cutoffs of <25 and <75% and a cutoff of ≥4 viable segments were less useful predictors of global LV recovery.

CONCLUSIONS

Based on a 50% transmural viability cutoff, patients with ≥10 viable+normal segments improve global LV function post revascularisation, while patients with fewer such segments do not. LGE-CMR is a simple and powerful tool for identifying which patients with impaired LV function will benefit from CABG.

TRIAL REGISTRATION

Research Ethics Committee Unique Identifier: NRES:05/Q1603/42. The study is listed on the Current Controlled Trials Registry: ISRCTN41388968.URL: http://www.controlled-trials.com.

Relation between regional and global systolic function in patients with ischemic cardiomyopathy after beta-blocker therapy or revascularization

BACKGROUND

To assess the relationship between improved regional and global myocardial function in patients with ischemic cardiomyopathy in response to beta-blocker therapy or revascularization.

MATERIALS AND METHODS

Cardiovascular magnetic resonance (CMR) was performed in 32 patients with ischemic cardiomyopathy before and 8 +/- 2 months after therapy. Patients were assigned clinically to beta-blocker therapy (n = 20) or revascularization (n = 12). CMR at baseline was performed to assess regional and global LV function at rest and under low-dose dobutamine. Wall thickening was analyzed in dysfunctional, adjacent, and remote segments. Follow-up CMR included rest function evaluation.

RESULTS

Augmentation of wall thickening during dobutamine at baseline was similar in dysfunctional, adjacent and remote segments in both patient groups. Therefore, baseline characteristics were similar for both patient groups. In both patient groups resting LV ejection fraction and end-systolic volume improved significantly (p < 0.05) at follow-up. Stepwise multivariate analysis revealed that improvement in global LV ejection fraction in the beta-blocker treated patients was significantly related to improved function of remote myocardium (p < 0.05), whereas in the revascularized patients improved function in dysfunctional and adjacent segments was more pronounced (p < 0.05).

CONCLUSION

In patients with chronic ischemic LV dysfunction, beta-Blocker therapy or revascularization resulted in a similar improvement of global systolic LV function. However, after beta-blocker therapy, improved global systolic function was mainly related to improved contraction of remote myocardium, whereas after revascularization the dysfunctional and adjacent regions contributed predominantly to the improved global systolic function.

Prognostic value of myocardial perfusion-gated SPECT in patients with ischemic cardiomyopathy

BACKGROUND

There are no extensive series in which risk stratification of patients with ischemic cardiomyopathy (IC) is based on their rest and exercise and scintigraphic characteristics. The purpose of our study was to analyze rest and exercise myocardial perfusion-gated SPECT variables for prognosis in patients with ischemic IC.

METHODS AND RESULTS

Prospective cohort study. A study was performed in 167 patients with IC who consecutively underwent rest myocardial perfusion-gated SPECT. In addition, stress SPECT was performed on 137 of these patients. During an average follow-up of 2.3 +/- 1.2 years, cardiac mortality (CM) was 17.4%. Independent predictors of CM in rest-gated SPECT were the positive criteria for myocardial viability (P = 0.027; Hazard risk, HR: 5.1; 95% CI: 1.2-21.4). In the 137 patients who underwent stress-gated SPECT, predictors were scintigraphic criteria for viability plus ischemia (P = 0.026; HR: 3.6; 95% CI: 1.16-11.2) and exercise duration < or = 5 minutes (P = 0.04; HR: 2.7; 95% CI: 1.01-7.36). Coronary angiography variables, performed in 111 patients, did not significantly modify the prognostic value of non-invasive testing.

CONCLUSION

Myocardial perfusion-gated SPECT improves prognostic stratification of patients with IC.

A randomized trial of on-pump beating heart and conventional cardioplegic arrest in coronary artery bypass surgery patients with impaired left ventricular function using cardiac magnetic resonance imaging and biochemical markers

BACKGROUND

Beating heart coronary artery bypass grafting (CABG) improves early postoperative cardiac function in patients with normal ventricular function, but its effect in patients with impaired function is uncertain. We compared a novel hybrid technique of on-pump beating heart CABG (ONBEAT) with conventional on-pump CABG (ONSTOP) in patients with impaired ventricular function.

METHODS AND RESULTS

In a single-center randomized trial, 50 patients with impaired ventricular function were randomly assigned to ONBEAT or ONSTOP. Patients underwent cardiac magnetic resonance imaging for function and delayed hyperenhancement early and later after surgery. Serial assessment of biochemical markers was also undertaken. Preoperative characteristics were well matched; cardiac index was 2.85+/-0.53 (ONBEAT) and 2.62+/-0.59 L x min(-1) x m(-2) (ONSTOP). Early after surgery, there was a trend toward a greater reduction in end-systolic volume index in ONSTOP patients versus ONBEAT (-9+/-8 versus -4+/-11 mL x m(-2); P=0.06). The changes were sustained and significant at 6 months (-14+/-18 versus -2+/-19 mL x m(-2); P=0.04). Furthermore, the incidence of new hyperenhancement at 6 days was higher in ONBEAT patients (P=0.05), with 6 of 17 (35%) sustaining 8.2+/-5.2 g of new hyperenhancement each versus 2 of 23 (9%) in the ONSTOP group, each with 9.8+/-9.0 g (P=0.86). Finally, median area under the curve for troponin was higher in ONBEAT at 461 (interquartile range, 226 to 1141) microg/L versus 160 (interquartile range, 98 to 357) microg/L for ONSTOP (P=0.002).

CONCLUSIONS

The incidence of new irreversible myocardial injury was significantly higher in ONBEAT than in ONSTOP patients. Furthermore, at 6 months, only ONSTOP patients demonstrated an improvement in ventricular geometry. The most likely mechanism is inadequate coronary perfusion to distal myocardial territories in patients with severe proximal coronary disease.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Left ventricular restoration: how important is the surgical treatment of ischemic heart failure trial?

If the Surgical Treatment of Ischemic Heart Failure (STICH) trial demonstrates that surgical therapy is superior to medical therapy, early aggressive evaluation of coronary artery disease as a potentially correctable cause of new-onset heart failure would be the preferred strategy. This strategy could tremendously change the treatment of ischemic heart disease. Confirming the STICH revascularization hypothesis will dramatically increase the use of coronary artery bypass grafting among the millions of patients now being medically treated without evaluation for an ischemic cause.

Oral treatment with probucol in a pharmacological dose has no beneficial effects on mortality in chronic ischemic heart failure after large myocardial infarction in rats

Cardiac remodeling after myocardial infarction is in part triggered and maintained by reactive oxygen species. Antioxidants such as probucol have shown positive short-term effects on these cardiac interstitial changes in different experimental models after intraperitoneal administration or after per-oral administration with a long pre-treatment period or in high doses. In this study, the long-term effects on mortality and cardiac remodeling were examined after induction of a large myocardial infarction in a clinical daily-life-like setting. Male Lewis rats were randomized to the study groups. Large anterolateral myocardial infarctions were induced or sham operations performed. The oral treatment was started after 48 h either with probucol or placebo after myocardial infarction and with placebo after sham operation. Induction of large myocardial infarctions led to changes of the left ventricular stiffness constants, a dilatation of the left ventricle and an increased interstitial fibrosis in the remote non-infarcted part. These changes were in tendency, but not significantly, reversed after treatment with probucol. The 6-month survival rates were 53.1% in the group probucol-myocardial infarction, 43.2% in the group placebo-myocardial infarction and 100% in the group after sham operation. There were no significant differences at Kaplan-Meier analysis between the groups after myocardial infarctions. Oral treatment with the antioxidant probucol started after myocardial infarction in a pharmacological dose does not have favourable effects on the long-term mortality in the chronic ischemic heart failure model in the rat.

Prediction of functional recovery after revascularization in patients with coronary artery disease and left ventricular dysfunction by gated FDG-PET

BACKGROUND

Traditionally, cardiac fluorodeoxyglucose (FDG) uptake is combined with regional perfusion for optimal evaluation of viability. Gated FDG-positron emission tomography (PET) may be an alternative technique for detection of viability because it permits combined assessment of glucose metabolism uptake and wall thickening (WT). In this study the value of FDG uptake and WT (analyzed from a stand-alone gated FDG-PET study) for the prediction of recovery of regional and global left ventricular (LV) function in patients with coronary artery disease undergoing revascularization is studied.

METHODS AND RESULTS

Thirty-eight patients with chronic coronary artery disease and LV dysfunction were included. Patients underwent gated FDG-PET to assess viability. Magnetic resonance imaging was performed before and 6 months after revascularization to assess regional and global LV function and LV volumes. Of the 213 revascularized dysfunctional segments, 133 (62%) exhibited functional recovery on follow-up magnetic resonance imaging. Receiver operating characteristic curve analysis indicated that a cutoff level for FDG uptake of 50% or greater yielded a sensitivity and specificity of 93% and 85%, respectively, on gated FDG-PET for prediction of improvement in regional function. Similarly, a cutoff level of 10% or greater for WT was optimal with a sensitivity and specificity of 89% and 78%, respectively. Improvement in LV ejection fraction was best predicted by the number of viable segments. Reverse LV remodeling could be predicted with a sensitivity and specificity of 89% and 65%, respectively, by use of FDG uptake of 50% or greater and 78% and 70%, respectively, by use of WT of 10% or greater.

CONCLUSION

Accurate prediction of outcome after revascularization (including improvement in regional and global LV function and reverse remodeling) is possible with gated FDG-PET by use of a threshold of 50% or greater for FDG uptake or a threshold of 10% or greater for WT.

Diagnostic and imaging considerations: role of viability

Left ventricular systolic dysfunction is a recognised feature of heart failure. In developed nations, the leading cause of left ventricular systolic dysfunction is coronary artery disease. Revascularisation is a treatment strategy for patients with predominant symptoms of heart failure and significant left ventricular dysfunction. Presence or absence of myocardial viability has been shown to affect outcome after revascularisation. There are various techniques to assess myocardial viability. However, limitations of current literature, lack of completed randomised trials and high peri-procedural trials create significant uncertainty about the optimal strategy. This review focuses on the role of non-invasive testing for myocardial viability in patients with left ventricular systolic dysfunction and heart failure and also outlines the pros and cons of each technique.

Increased left atrial volume index is an independent predictor of raised serum natriuretic peptide in patients with suspected heart failure but normal left ventricular ejection fraction: Implication for diagnosis of diastolic heart failure

BACKGROUND

Left atrial volume index (LAVI) is increasingly recognised as a relatively load-independent marker of left ventricular (LV) filling pressures. We assessed the capacity of LAVI to predict LV diastolic dysfunction in comparison with N-terminal pro B-type natriuretic peptide (NTproBNP) in patients with suspected heart failure and a normal ejection fraction (EF).

METHODS

137 patients with suspected heart failure (HF), referred from the community for echocardiography, prospectively underwent Doppler echocardiography, LAVI and NTproBNP estimation. Raised LAVI and reduced LV systolic function were defined as >26 ml/m2 and LV EF <50% respectively.

RESULTS

Of 137 patients, 21 were excluded (2 with significant mitral valve disease and 19 with atrial fibrillation). Of the remaining 116 subjects, 92 showed normal LV systolic function. The univariate predictors of serum log NTproBNP were age (p < 0.001), LA dimension (p = 0.001), LAVI (p < 0.001), A wave (p = 0.001), E:A (p = 0.07) and septal wall thickness (p = 0.004). However on multivariate analysis, LAVI was found to be the most consistent and significant predictor of NTproBNP. The area under the curve of the receiver operating characteristic (ROC) curve for NTproBNP in detecting patients with LVEF > or = 50% and LAVI >26 ml/m2 was 0.81 (p < 0.0001) and for patients with LAVI > 26 ml/m2 with and without LVEF > or = 50% was 0.82 (p < 0.0001).

CONCLUSION

This data confirms that LAVI on resting echocardiography, specifically in patients with suspected HF and normal LV systolic function is a powerful independent predictor of LV diastolic dysfunction as predicted by serum NTproBNP. In a population with a high suspicion of diastolic heart failure, LAVI may significantly contribute to diagnostic precision.

Surgical Ventricular Restoration: The RESTORE Group Experience

Congestive heart failure may be caused by late left ventricular (LV) dilation following anterior infarction. Early reperfusion prevents transmural necrosis, and makes the infarcted segment akinetic rather than dyskinetic. Surgical ventricular restoration (SVR) reduces LV volume and creates a more elliptical chamber by excluding scar in either akinetic or dyskinetic segments. The international RESTORE group applied SVR in a registry of 1198 post-infarction patients between 1998 and 2003. Early and late outcomes were examined and risk factors identified.Concomitant procedures included coronary artery bypass grafting in 95%, mitral valve repair in 22%, and mitral valve replacement in 1%. Overall 30-day mortality after SVR was 5.3% (8.7% with mitral repair vs. 4.0% without repair, p < .001) Perioperative mechanical support was uncommon (< 9%). Global systolic function improved postoperatively, as ejection fraction increased from 29.6 +/- 11.0% to 39.5 +/- 12.3% (p < .001) and left ventricular end systolic volume index decreased from 80.4 +/- 51.4 ml/m(2) to 56.6 +/- 34.3 ml/m(2) (p < .001). Overall 5-year survival was 68.6 +/- 2.8%, Logistic regression analysis identified EF < or = 30%, LVESVI > o = 80 ml/m(2), advanced NYHA functional class, and age > or =75 years as risk factors for death. Five-year freedom from hospital readmission for CHF was 78%. Preoperatively, 67% of patients were class III or IV, and postoperatively 85% were class I or II.SVR improves ventricular function and is highly effective therapy in the treatment of ischemic cardiomyopathy with excellent 5-year outcome.

Ventricular Structure and Surgical History

The Reviews report will establish guidelines that underlie why the "restoration concept" may develop a paradigm shift in thinking, by addressing the geometric underpinnings of heart failure and their evolution. This presentation will (a) show that the underlying structure of the failing dilated heart involves a cardiac architectural change from the normal elliptical shape toward a dilated spherical form, (b) define the anatomic framework of this shape change, (c) convey the functional characteristics of heart function that result from this architectural underpinning, (d) describe the pattern of CHF development, (e) indicate imaging measurement guidelines to follow as heart form adversely changes from ellipse to sphere, (f) identify how such architectural changes alter prognosis, and (g) develop a historical evolution of surgical approaches to alter form to improve function to create the background for subsequent RESTORE team reports of current restoration to treat CHF and its complications.

Regional left ventricular perfusion and function in patients presenting to the emergency department with chest pain and no ST-segment elevation†

AIMS

We hypothesized that the assessment of left ventricular regional function (RF) and myocardial perfusion (MP) will provide incremental value over routine evaluation in patients who present to the emergency department (ED) with chest pain (CP) and no ST-segment elevation.

METHODS AND RESULTS

In addition to routine clinical evaluation, patients with suspected cardiac CP and no ST-segment elevation were evaluated in the ED for RF and MP using contrast echocardiography (CE). Cardiac-related death, acute myocardial infarction, unstable angina pectoris, congestive heart failure (CHF), and revascularization were considered as events within 48 h (early). Of the 1017 patients studied, 166 (16.3%) had early events. Adding RF increased the prognostic information of clinical and EKG variables significantly (Bonferroni corrected P<0.0001) for predicting these events. When MP was added, significant additional prognostic information was obtained (Bonferroni corrected P=0.0002). All patients were followed for a median of 7.7 months (25th-75th percentiles: 2.7-12.5) Of these, 292 (28.7%) had events. Adding RF increased the prognostic information of clinical and EKG variables for determining the risk of events significantly (Bonferroni corrected P<0.0001), which was further increased by adding MP (Bonferroni corrected P<0.0001).

CONCLUSION

Early assessment of RF on CE adds significant diagnostic and prognostic value to routine evaluation in patients presenting to the ED with suspected cardiac CP and no ST-segment elevation. MP provides additional significant value. CE could be a valuable tool in the early triage and management of CP patients presenting to the ED.

Stress echocardiography for the diagnosis and risk stratification of patients with suspected or known coronary artery disease: a critical appraisal. Supported by the British Society of Echocardiography

Stress echocardiography today has matured into a robust and reliable technique not only for the diagnosis of suspected coronary artery disease (CAD) but also for the accurate risk stratification of patients with suspected and established CAD. This is mainly because of rapid advances in image acquisition, digital display, and the development of harmonic and contrast imaging. Stress echocardiography today is also utilised in patients with heart failure both for assessing the cause of heart failure and determining the extent of hibernating myocardium. With advances in myocardial perfusion imaging, stress echocardiography now allows simultaneous assessment of myocardial function and perfusion. Tissue Doppler imaging allows quantitation of wall motion. Ready availability and reliability makes stress echocardiography a cost effective technique for the assessment of CAD.

Assessment of Myocardial Viability Using Myocardial Contrast Echocardiography

Myocardial contrast echocardiography (MCE) is a technique that uses microbubbles as a tracer during simultaneous ultrasound of the heart. The microbubbles can be used to provide quantitative information regarding the adequacy of myocardial blood flow (MBF), as well as the spatial extent of microvascular integrity. In acute myocardial infarction, MCE can identify the presence of collateral flow within the risk area, and can therefore predict preservation of myocardial viability and ultimate infarct size even prior to reperfusion. After reperfusion, the extent of microvascular no-reflow can be determined, and has significant implications for recovery of left ventricular function. In chronic ischemic heart disease, MCE has also been shown to successfully differentiate viable from necrotic myocardium. This technique can accurately predict recovery of function after revascularization. More importantly, MCE can be used to identify viable segments that may help to prevent infarct expansion and remodeling, and thus improve patient outcomes.

Opposite patterns of left ventricular remodeling after coronary revascularization in patients with ischemic cardiomyopathy: role of myocardial viability

BACKGROUND

In patients with ischemic cardiomyopathy, left ventricular (LV) remodeling is an important prognostic indicator. The precise relation between viable myocardium, revascularization, and ongoing or reversed remodeling is unknown and was evaluated in the present study.

METHODS AND RESULTS

A total of 100 patients with ischemic cardiomyopathy underwent dobutamine stress echocardiography to assess myocardial viability and LV geometry (volumes and shape). At a mean of 10.2 months and 4.5 years after revascularization, resting echocardiography was repeated to evaluate LV remodeling. Long-term follow-up (mean 5+/-2 years) data were obtained. According to dobutamine stress echocardiography, 44 patients (44%) were defined as viable (> or =4 viable segments) and 56 as nonviable. After revascularization, 40 patients (43%) had ongoing LV remodeling and 53 (57%) did not (in 7 patients who died early after revascularization, postoperative echocardiographic evaluation was not available). On multivariable analysis, the number of viable segments was the only predictor of ongoing LV remodeling (OR 0.60, 95% CI 0.48 to 0.75; P<0.0001). The likelihood of LV remodeling decreased as the number of viable segments increased. During the follow-up, reverse remodeling was present in viable patients, whereas in nonviable patients, LV volumes significantly increased, which indicates ongoing LV remodeling. At follow-up, viable patients also showed a persistent improvement of heart failure symptoms and fewer cardiac events than nonviable patients (P<0.05).

CONCLUSIONS

In patients with ischemic cardiomyopathy, a substantial amount of viable myocardium prevents ongoing LV remodeling after revascularization and is associated with persistent improvement of symptoms and better outcome.

Myocardial contrast echocardiography predicts left ventricular remodelling after acute myocardial infarction

BACKGROUND

We investigated whether the extent of residual myocardial viability demonstrated by myocardial contrast echocardiography (MCE) predicts the degree of left ventricular (LV) remodelling after acute myocardial infarction as assessed by cardiovascular magnetic resonance.

METHODS

Accordingly, 25 patients underwent MCE 5 to 7 days after acute myocardial infarction followed by cardiovascular magnetic resonance assessment of LV end-diastolic volume, LV end-systolic volume, and LV ejection fraction. A contrast perfusion index was calculated within the infarct-related territory.

RESULTS

LV end-diastolic and end-systolic volumes were significantly smaller (138 +/- 38 vs 188 +/- 43 mL, P =.008, and 86 +/- 35 vs 119 +/- 49 mL, P =.01, respectively) and LV ejection fraction was significantly higher (52 +/- 5.4 vs 31.5 +/- 3.2%, P> =.02) in patients showing good myocardial viability (contrast perfusion index </= 1.5) compared with those without viability. MCE was the only multivariate predictor of LV volumes and LV ejection fraction at 2 weeks and 6 months.

CONCLUSIONS

The extent of residual myocardial viability as demonstrated by MCE predicts the degree of LV remodelling after acute myocardial infarction.

Usefulness of left atrial volume as a predictor of mortality in patients with ischemic cardiomyopathy

Left atrial (LA) volume is a load-independent marker of left ventricular diastolic function. To determine the value of LA volume to predict mortality in patients with ischemic cardiomyopathy, clinical and echocardiographic variables, including Doppler parameters, were evaluated in 109 patients with ischemic cardiomyopathy. LA volume was the only independent predictor of mortality (hazard ratio 1.03, 95% confidence interval 1.001 to 1.057, p = 0.03).

Prognostic and therapeutic implications of myocardial viability in patients with heart failure

Substantial progress has been made in understanding the pathophysiology of regional and global left ventricular (LV) dysfunction and the states of hibernation and stunning in patients with heart failure. The clinical literature on the use of noninvasive imaging to assess myocardial viability has evolved from predicting improvement in regional LV function to predicting patient-related outcomes, including heart failure symptom improvement and survival after revascularization. A substantial body of observational cohort data demonstrates that mortality risk is high in patients with coronary artery disease and LV dysfunction who have substantial viable myocardium, and that risk is reduced by revascularization. Thus, noninvasive imaging of myocardial ischemia and viability can provide important prognostic information in patients with heart failure and LV dysfunction, and provide a signal of the potential benefit of revascularization.

Heart failure therapy at a crossroad: are there limits to the neurohormonal model?

The advent of neurohormonal blockade in heart failure (HF) has been an overwhelming success, but current evidence points to a ceiling effect as newer neurohormonal targets are exploited in an incremental manner. This has lead us to question whether the neurohormonal model of HF can be sustained by simply stacking multiple neurohormonal or cytokine blockers together as treatment. A unifying theme in some of these disparate trials relates to either a lack of efficacy or, more importantly, adversity resulting in regression of already achieved benefits. It is our contention that the available evidence has uncovered the remarkable complexity of interaction within the context of the neurohormonal construct. As we stand at a crossroad in HF and begin to fervently pursue non-neurohormonal therapeutic targets, we must also direct attention at navigating the multifaceted labyrinth of the neurohormonal model that has led to the current imbroglio.

Assessment of myocardial perfusion with intravenous contrast echocardiography: comparison with (99) Tc-tetrofosmin single photon emission computed tomography and dobutamine echocardiography

The aim of the study was to evaluate the accuracy of intermittent, harmonic power Doppler (HPD) during intravenous Levovist infusion in identifying myocardial perfusion abnormalities in patients with recent infarction. Fifty-five patients with first acute myocardial infarction, successfully treated by primary PTCA, were studied after 1 month by myocardial contrast echocardiography (MCE), 99mTc tetrofosmin single photon emission computed tomography (SPECT), and low dose dobutamine echocardiography (DE). Scoring myocardial perfusion as normal, moderately, or severely reduced; MCE and SPECT were in agreement in 71% of segments(k = 0.414). Discordance was mainly due to ventricular walls with normal enhancement by MCE and moderate perfusion abnormalities by SPECT. Scoring perfusion as present or absent, the agreement significantly improved up to 86% (k = 0.59). Sensitivity and specificity of HPD for identifying SPECT perfusion defects were 63% and 93%, respectively. The agreement between MCE and SPECT was higher(85%, k = 0.627)in patients with anterior infarction. An improvement in regional contractile function was noted after dobutamine in 79 dysfunctional segments. A normal perfusion or a moderate perfusion defect by MCE were detected in 71 of 79 of these segments, while a severe perfusion defect was observed in 59 of 85 ventricular segments without dobutamine-induced wall-motion improvement. Sensitivity and specificity by HPD in detecting segments with contractile reserve were 90% and 69%, respectively. Thus, intermittent HPD during Levovist infusion allows myocardial perfusion abnormalities to be detected in patients with recent infarction. This method has a limited sensitivity but a high specificity in detecting SPECT perfusion defects, and a good sensitivity but a limited specificity in detecting contractile reserve.

Precardiopulmonary bypass right ventricular function is associated with poor outcome after coronary artery bypass grafting in patients with severe left ventricular systolic dysfunction

Patients with severe left ventricular systolic dysfunction (LVSD) undergoing coronary artery bypass grafting (CABG) have an increased risk for morbidity and mortality. The purpose of this study was to assess the association of pre-CABG right ventricular (RV) function with outcome for patients with severe LVSD. We performed a retrospective evaluation of 41 patients with severe LVSD (left ventricular ejection fraction [LVEF] < or =25%) scheduled for nonemergent CABG. Data were obtained from review of medical records, transesophageal echocardiography tapes, and phone interview. The pre- and post-cardiopulmonary bypass (CPB) LVEF and the RV fractional area of contraction (RVFAC) were calculated by using intraoperative transesophageal echocardiography. Group 1 patients had an RVFAC < or =35% (n = 7), whereas Group 2 patients had RVFAC >35% (n = 34). The durations of mechanical ventilation and of intensive care unit and hospital stays are presented as the median. Pre-CABG LVEF was similar between Groups 1 and 2 (15.8% +/- 3.3% versus 17.8% +/- 3.9%). Compared with Group 2, Group 1 patients required greater duration of mechanical ventilation (12 days versus 1 day; P < 0.01), longer intensive care unit (14 versus 2 days; P < 0.01) and hospital (14 versus 7 days; P = 0.02) stays, had a more frequent incidence and severity of LV diastolic dysfunction, and had a smaller change in LVEF immediately after CPB (4.1% +/- 8.3% versus 12.5% +/- 9.2%; P = 0.03). All Group 1 patients died of cardiac causes within 2 yr of surgery; five died during the same hospital admission. Three Group 2 patients died: one of colon cancer at 18 mo after CABG and two of cardiac causes 24 and 48 mo after surgery. A fourth patient was awaiting cardiac transplantation 4 yr after surgery. The remaining Group 2 patients were New York Heart Association Classification I or II. For patients with severe LVSD undergoing CABG, pre-CPB RV dysfunction was associated with poor outcome. Patients with RVFAC >35% had a relatively uneventful perioperative course and good long-term survival, whereas patients with RVFAC < or =35% had a poor early and late outcome. Assessment of RV function is useful to further assess the risk of CABG.

IMPLICATIONS

Right ventricular function before cardiopulmonary bypass is associated with poor outcome after coronary artery surgery in patients with poor left ventricular function.

Long-term outcome after coronary artery bypass grafting in patients with severe left ventricular dysfunction

BACKGROUND

The aim of this study was to define the potential for long-term survival with severe left ventricular dysfunction after coronary bypass and to quantify any improvement in overall functional status.

METHODS

Left ventricular dysfunction was confirmed preoperatively and the long-term survival and functional outcome after bypass was determined by follow-up studies obtained during the span of a decade.

RESULTS

From 1/1990 to 12/1999, 86 patients with severe left ventricular dysfunction (mean ejection fraction, 0.18 +/- 0.03; range, 0.10 to 0.20) underwent coronary artery bypass grafting. There were 10 perioperative deaths (11% mortality). The mean survival was 55 months (standard deviation +/- 34 months; range, 2 to 141 months) with an actual 5-year survival rate of 59% (actuarial 5-year 65%, 10-year 33%). Echocardiography obtained between 1 and 6 months, 6 months and 1 year, 1 and 2 years, 2 and 4 years, 4 and 6 years, and 6 and 11 years showed the ejection fraction improved to 0.29 +/- 0.08 (p < 0.001), 0.31 +/- 0.14 (p < 0.002), 0.35 +/- 0.08 (p < 0.001), 0.27 +/- 0.10 (p = 0.002), 0.36 +/- 0.14 (p = 0.004), and 0.30 +/- 0.11 (p = 0.004), respectively. At 1 to 6 months, 6 months to 1 year, and 1 to 2 years, the diastolic left ventricular dimension was unchanged, but the systolic left ventricular dimension decreased significantly from 5.02 +/- 0.77 cm to 4.26 +/- 0.91 cm (p = 0.046), 3.98 +/- 1.43 cm (p = 0.08), and 4.10 +/- 1.14 cm (p = 0.07). The preoperative New York Heart Association classification for all patients improved from 2.8 +/- 0.8 to 1.6 +/- 0.7 (p < 0.001) after a mean of 53 months (standard deviation +/- 34 months).

CONCLUSIONS

Patients with severe left ventricular dysfunction can derive long-term benefit from coronary bypass through improved left ventricular contractility as documented by a significantly decreased systolic left ventricular dimension and increased ejection fraction. Successful bypass is associated with a 59% actual 5-year survival rate and significantly improved New York Heart Association functional class.

Usefulness of intravenous myocardial contrast echoardiography in the early left ventricular remodeling in acute myocardial infarction

The aim of this study was to assess the role of intravenous myocardial contrast echocardiography (IMCE) in the prediction of left ventricular (LV) remodeling in patients with acute myocardial infarction (AMI). Sixty-three patients with AMI, who were successfully treated with acute coronary angioplasty, underwent IMCE and low-dose dobutamine echocardiography during hospital admission. IMCE was graded semiquantitatively on a score of 0 (no visible contrast effect), 0.5 (patchy myocardial contrast enhancement), and 1 (homogenous contrast effect). Patients were considered to have microvascular impairment if <50% of segments within the infarct-related area had score of 1. A mean perfusion score index was calculated for each patient. Patients with a good perfusion at IMCE (IMCE+) showed a lower creatine kinase peak (p = 0.001) and lower creatine kinase-MB (p = 0.01), and a better baseline regional contractile function compared with patients who had negative results at IMCE (IMCE-) (p <0.0001) and a higher amount of myocardial viability at low-dose dobutamine echocardiography (p = 0.03). At follow-up, a higher improvement in regional systolic function (p = 0.0006) was observed in IMCE+ patients, whereas IMCE- patients showed an evident increase in LV end-diastolic volume from baseline to 6-month follow-up (p <0.0001), implying LV remodeling, which has been associated with a higher incidence of adverse cardiac events (p = 0.005). By stepwise multiple regression analysis, microvascular impairment at IMCE was a significant independent predictor of LV remodeling (p <0.0001). Thus, IMCE seems to be an important diagnostic tool, able to predict LV remodeling in patients with AMI.

Left ventricular remodeling and functional mitral regurgitation: mechanisms and therapy

Myocardial damage that results in dysfunction and remodeling changes left ventricular shape and size. Mitral competence requires the functional integrity of all components of the mitral apparatus. Progressive remodeling ultimately leads to geometric distortion of multiple elements of the mitral apparatus, resulting in functional mitral regurgitation (MR). In this article, we examine the mechanisms of functional MR in the remodeled ventricle. Surgical treatment should aim to correct all abnormalities of the mitral apparatus. These include (1) revascularization of viable myocardium, (2) reduction of ventricular volume and restoration of shape, (3) realignment of papillary muscles, and (4) reduction of annular orifice size.